Saptalis Pharmaceuticals LLC v. MSN Pharmaceuticals Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Saptalis Pharmaceuticals, LLC (New York) and Appili Therapeutics Inc. (Canada)
  • Defendant: MSN Pharmaceuticals, Inc. (Delaware) and MSN Laboratories Pvt. Ltd. (India)
  • Plaintiff’s Counsel: McCarter & English, LLP; Husch Blackwell LLP
• Case Identification: 2:26-cv-01084, D.N.J., 02/03/2026
• Venue Allegations: Plaintiffs allege venue is proper for MSN Pharmaceuticals, Inc. because it has its principal place of business in the District of New Jersey. Venue is alleged to be proper for MSN Laboratories Pvt. Ltd., a foreign entity, as it may be sued in any judicial district.
• Core Dispute: Plaintiffs allege that Defendants' submission of an Abbreviated New Drug Application (ANDA) to the FDA for a generic metronidazole oral suspension constitutes an act of patent infringement under the Hatch-Waxman Act.
• Technical Context: The technology relates to taste-masked oral liquid formulations of metronidazole, an antimicrobial drug known for its bitter taste, intended to improve palatability and patient compliance, particularly for pediatric and geriatric populations.
• Key Procedural History: The lawsuit was initiated in response to Defendants' filing of ANDA No. 221087 and a corresponding Paragraph IV certification notice letter, which asserted that the patents-in-suit are invalid, unenforceable, and/or would not be infringed by the proposed generic product.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 11,541,035 - "Oral Formulations of Metronidazole and Methods of Treating an Infection Using Same"

The Invention Explained

• Problem Addressed: The patent describes the antimicrobial drug metronidazole as having a bitter taste and an unpleasant metallic aftertaste, which can deter patient compliance with dosing regimens ’035 Patent, col. 1:47-49 Existing solid dosage forms are difficult for patients with dysphagia (difficulty swallowing), such as children and the elderly, to take ’035 Patent, col. 1:50-53 Alternative liquid formulations, such as metronidazole benzoate suspensions, are noted to have slower absorption rates, which may make them inappropriate for treating acute infections ’035 Patent, col. 2:56-62
• The Patented Solution: The invention is an oral pharmaceutical composition that aims to mask the unpleasant taste of metronidazole by formulating it as a liquid suspension containing magnesium aluminum silicate ’035 Patent, abstract The patent suggests that the combination of the active ingredient with this specific suspending agent, along with other excipients, effectively masks the taste without compromising the drug's bioavailability, thus providing a palatable and therapeutically equivalent alternative to tablets ’035 Patent, col. 18:20-29 ’035 Patent, col. 18:60-65
• Technical Importance: This approach seeks to provide a ready-to-use, taste-masked liquid formulation of metronidazole that is suitable for patients who cannot swallow solid pills, thereby potentially improving adherence to treatment for infections ’035 Patent, col. 1:8-14

Key Claims at a Glance

The complaint alleges infringement of one or more claims without specifying which ones Compl. ¶39 Independent claim 1 is a representative composition claim.

• Independent Claim 1: An oral pharmaceutical composition comprising:
  • metronidazole, sucrose, glycerin, purified water,
  • magnesium aluminum silicate,
  • microcrystalline cellulose, sucralose,
  • sodium phosphate,
  • one or more preservatives,
  • strawberry flavoring agent and peppermint flavoring agent.
    The complaint reserves the right to assert additional claims, including dependent claims Compl. ¶39

U.S. Patent No. 12,257,236 - "Oral Formulations of Metronidazole and Methods of Treating an Infection Using Same"

The Invention Explained

• Problem Addressed: As a continuation of the application leading to the '035 Patent, the '236 Patent addresses the same technical problems: the bitter taste of metronidazole and the difficulty certain patient populations have with swallowing solid dosage forms ’236 Patent, col. 1:49-55
• The Patented Solution: The '236 Patent similarly discloses an oral liquid suspension of metronidazole that uses magnesium aluminum silicate for taste-masking ’236 Patent, abstract The claims in this patent provide different scopes of protection for the core invention, with some claims adding specific limitations, such as the nature of the silicate used ’236 Patent, claim 12
• Technical Importance: This patent extends the intellectual property protection around the core taste-masked formulation, providing variations on the composition that may be important for market positioning and enforcement.

Key Claims at a Glance

The complaint alleges infringement of one or more claims without specification Compl. ¶61 Independent claim 12 is a representative composition claim.

• Independent Claim 12: An oral pharmaceutical liquid suspension comprising:
  • a) metronidazole or a pharmaceutically acceptable salt thereof; and
  • b) magnesium aluminum silicate, wherein the magnesium aluminum silicate is a natural product.
    The complaint reserves the right to assert additional claims, including dependent claims Compl. ¶61

III. The Accused Instrumentality

Product Identification

• The accused instrumentality is the "MSN ANDA Product," identified as a "metronidazole oral suspension, 500 mg/5 mL" for which Defendants have sought FDA approval via ANDA No. 221087 Compl. ¶5

Functionality and Market Context

• The complaint alleges that the MSN ANDA Product is a generic version of LIKMEZ®, a metronidazole oral suspension marketed by Plaintiff Saptalis Compl. ¶31 By filing the ANDA, Defendants have represented to the FDA that their product will possess the same active ingredient, method of administration, dosage form, and strength as LIKMEZ®, and that it will be bioequivalent Compl. ¶32
• The filing of the ANDA is alleged to be an act of infringement under 35 U.S.C. § 271(e)(2), which makes the submission of an application to the FDA for a generic drug an act of infringement if the drug would infringe a valid patent upon commercialization Compl. ¶30

No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

The complaint does not provide a detailed claim chart or specific evidence of the accused product's composition. The infringement allegations are based on the premise that the MSN ANDA Product, as a proposed generic equivalent to LIKMEZ®, will necessarily contain the elements recited in the patents-in-suit, which are listed in the FDA's Orange Book for LIKMEZ® Compl. ¶¶28, 32

'035 Patent Infringement Allegations

'236 Patent Infringement Allegations

• Identified Points of Contention:
  • Evidentiary Questions: A primary issue will be factual and evidentiary. The complaint's allegations are based on the representation of generic equivalence. Discovery into the contents of the confidential ANDA will be required to determine if the MSN ANDA Product's formulation literally contains every component recited in the asserted claims, including the specific combination of excipients and flavorings.
  • Scope Questions: For the '236 Patent, a key dispute may arise over the claim term "natural product." The infringement analysis will question whether the specific type of magnesium aluminum silicate used by Defendants, if any, falls within the scope of this term, or if it could be characterized as synthetic or semi-synthetic, potentially avoiding literal infringement of claims with this limitation.

V. Key Claim Terms for Construction

• The Term: "magnesium aluminum silicate"

• Context and Importance: This is the primary excipient identified in the patents as providing the novel taste-masking function. The outcome of the case may depend on whether the suspending agent used in the MSN ANDA Product falls within the scope of this term. Practitioners may focus on this term because if Defendants use an alternative, non-silicate-based suspending agent, they may have a strong non-infringement argument.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The specification describes the material's function as a "suspending agent" that contributes to taste masking through adsorption and viscosity ’035 Patent, col. 18:20-29 ’035 Patent, col. 18:60-65 It also mentions both natural clay blends ("Veegum™") and synthetic versions like "magnesium aluminometasilicate" ("Neusilin™") ’035 Patent, col. 4:3-4 ’035 Patent, col. 18:55-57, which could support construing the term to cover a class of related chemical compounds.
  • Evidence for a Narrower Interpretation: The specification repeatedly references specific commercial grades, such as "VEEGUM™ HV" (Type IC), and provides a detailed table of different types (IA, IB, IC, IIA) ’035 Patent, col. 19:62-67 ’035 Patent, Table A A party could argue that these specific embodiments limit the term to smectite clays with particular properties, excluding other silicate compounds.

• The Term: "natural product" (from '236 Patent, claim 12)

• Context and Importance: This limitation distinguishes claim 12 of the '236 Patent from broader claims in the '035 Patent. Infringement will hinge on both the composition of the accused product and the legal definition of this term. If Defendants' formulation uses a synthetic silicate, this claim may not be infringed.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: The specification explicitly states, "In some embodiments, the magnesium aluminum silicate is a natural product," and identifies Veegum™, a refined smectite clay, as such ’236 Patent, col. 4:1-2 ’236 Patent, col. 18:36-39 This suggests that materials derived from natural mineral sources, even if processed, fall within the term's scope.
  • Evidence for a Narrower Interpretation: The specification draws a direct contrast: "In some embodiments, the magnesium aluminum silicate is synthetic" ’236 Patent, col. 4:3-4 A defendant might argue that extensive purification or chemical modification of a mined clay renders it non-natural, and the patent's own language creates a clear demarcation between the two categories.

VI. Other Allegations

• Indirect Infringement: The complaint alleges active inducement of infringement under 35 U.S.C. § 271(b) (Compl. ¶¶40, 62). The basis for this allegation is that upon FDA approval, Defendants intend to market the MSN ANDA Product with instructions and package inserts that will encourage and instruct medical professionals and patients to administer the product, thereby directly infringing the patents' claims. The complaint also alleges Defendants have knowledge of the patents (Compl. ¶¶42, 64).
• Willful Infringement: While the complaint does not use the term "willful," it lays the groundwork for such a claim by alleging that Defendants "have been aware of the existence" of the patents-in-suit and "have no reasonable basis for believing" that their product will not infringe (Compl. ¶¶45, 67). These allegations pertain to potential post-launch commercial activity for which Plaintiffs seek a declaratory judgment.

VII. Analyst’s Conclusion: Key Questions for the Case

The resolution of this Hatch-Waxman litigation will likely depend on the answers to two central questions for the court:

1. A core issue will be one of factual correspondence: Does the specific formulation detailed in Defendants' confidential ANDA contain every element recited in the asserted composition claims? The case will turn on whether Defendants' product includes not only metronidazole but also the key taste-masking agent, magnesium aluminum silicate, in combination with the other claimed excipients.

2. A secondary question will be one of definitional scope, particularly for the '236 Patent: How should the term "natural product," as applied to magnesium aluminum silicate, be construed? This determination will be critical to the infringement analysis if Defendants' formulation contains a synthetic or highly processed version of the silicate.